U.S. patent application number 11/645211 was filed with the patent office on 2008-06-26 for adjustable brake device.
This patent application is currently assigned to Nokia Corporation. Invention is credited to Ilpo Kauhaniemi, Joonas Ryynanen, Matti Ryynanen, Tessa Ryynanen.
Application Number | 20080150458 11/645211 |
Document ID | / |
Family ID | 39541833 |
Filed Date | 2008-06-26 |
United States Patent
Application |
20080150458 |
Kind Code |
A1 |
Ryynanen; Matti ; et
al. |
June 26, 2008 |
Adjustable brake device
Abstract
The invention relates to an adjustable brake device that can be
used in conjunction with a hinge mechanism of a folding electronic
device, e.g. a clamshell mobile phone. The adjustable brake device
comprises a brake actuator that is able to generate a braking force
responsive to a magnetic flux directed to the brake actuator and a
magnetic circuit that has a magnetizing device arranged to generate
the magnetic flux and a magnetic path arranged to conduct the
magnetic flux from the magnetizing device to the brake actuator. At
least two elements of the magnetic circuit are movable with respect
to each other. A mutual position of the at least two elements can
be used for determining strength of the magnetic flux directed to
the brake actuator. The braking force can be adjusted in a
relatively simple way by adjusting the mutual position of the
movable parts of the magnetic circuit.
Inventors: |
Ryynanen; Matti; (Espoo,
FI) ; Ryynanen; Joonas; (Espoo, FI) ;
Ryynanen; Tessa; (Helsinki, FI) ; Kauhaniemi;
Ilpo; (Vantaa, FI) |
Correspondence
Address: |
WARE FRESSOLA VAN DER SLUYS & ADOLPHSON, LLP
BRADFORD GREEN, BUILDING 5, 755 MAIN STREET, P O BOX 224
MONROE
CT
06468
US
|
Assignee: |
Nokia Corporation
|
Family ID: |
39541833 |
Appl. No.: |
11/645211 |
Filed: |
December 22, 2006 |
Current U.S.
Class: |
318/362 ;
188/267 |
Current CPC
Class: |
F16D 57/002 20130101;
F16F 15/03 20130101 |
Class at
Publication: |
318/362 ;
188/267 |
International
Class: |
F16F 15/03 20060101
F16F015/03 |
Claims
1. An adjustable brake device, comprising: a brake actuator
arranged to generate a braking force responsive to a magnetic flux
directed to said brake actuator, and a magnetic circuit arranged to
generate said magnetic flux and arranged to conduct said magnetic
flux to said brake actuator, wherein a first element of said
magnetic circuit is movable with respect to a second element of
said magnetic circuit and a mutual position of said first element
and said second element is arranged to at least partly determine
strength of said magnetic flux.
2. An adjustable brake device according to claim 1, wherein said
magnetic circuit comprises a bypass magnetic path arranged to
conduct another magnetic flux to bypass said brake actuator, a
change in the mutual position of said first element and said second
element arranged to increase strength of the other magnetic flux as
a response to a situation in which said change causes a decrease in
the strength of said magnetic flux directed to said brake
actuator.
3. An adjustable brake device according to claim 1, wherein said
magnetic circuit comprises a coil of electrical conductor capable
of carrying magnetizing electrical current for generating said
magnetic flux.
4. An adjustable brake device according to claim 1, wherein said
first element of said magnetic circuit comprises a permanent magnet
having a cylindrical shape and a magnetizing direction
perpendicular to an axis of said cylindrical shape, the strength of
said magnetic flux arranged to be changed as a response to a
situation in which said permanent magnet is rotated around said
axis.
5. An adjustable brake device according to claim 4, comprising a
coil of electrical conductor arranged to carry an electrical
current for producing a magnetic field that tends to rotate said
permanent magnet around said axis.
6. An adjustable brake device according to claim 1, wherein said
first element of said magnetic circuit comprises a permanent magnet
having a cylindrical shape and a magnetizing direction parallel
with an axis of said cylindrical shape, the strength of said
magnetic flux arranged to be changed as a response to a situation
in which said permanent magnet is moved in a direction of said
axis.
7. An adjustable brake device according to claim 6, comprising a
coil of electrical conductor arranged to carry an electrical
current for producing a magnetic field that tends to move said
first element in the direction of said axis.
8. An adjustable brake device according to claim 1, wherein said
brake actuator comprises ferrofluid having viscosity responsive to
the magnetic flux directed to said brake actuator, said viscosity
being arranged to produce the braking force on a surface of solid
material in contact with said ferrofluid as a response to a
situation in which said surface moves with respect to said
ferrofluid.
9. An adjustable brake device according to claim 1, wherein said
brake actuator comprises magnetorheological fluid having viscosity
responsive to the magnetic flux directed to said brake actuator,
said viscosity being arranged to produce the braking force on a
surface of solid material in contact with said magnetorheological
fluid as a response to a situation in which said surface moves with
respect to said magnetorheological fluid.
10. An adjustable brake device according to claim 1, wherein said
brake actuator comprises a brake disk and a brake pad arranged to
be pressed against said brake disk as a response to a situation in
which said magnetic flux is conducted into said brake actuator.
11. An adjustable brake device according to claim 1, wherein said
brake actuator comprises a brake drum and a brake shoe arranged to
be pressed against said brake drum as a response to a situation in
which said magnetic flux is conducted into said brake actuator.
12. A hinge mechanism, comprising: a first part and a second part
that are able to turn with respect to each other, a brake actuator
arranged to generate a braking force responsive to a magnetic flux
directed to said brake actuator, said braking force being able to
damp turning movement of said first part with respect to said
second part, and a magnetic circuit arranged to generate said
magnetic flux and arranged to conduct said magnetic flux to said
brake actuator, wherein a first element of said magnetic circuit is
movable with respect to a second element of said magnetic circuit
and a mutual position of said first element and said second element
is arranged to at least partly determine strength of said magnetic
flux.
13. A hinge mechanism according to claim 12, wherein said magnetic
circuit comprises a bypass magnetic path arranged to conduct
another magnetic flux to bypass said brake actuator, a change in
the mutual position of said first element and said second element
arranged to increase strength of the other magnetic flux as a
response to a situation in which said change causes a decrease in
the strength of said magnetic flux directed to said brake
actuator.
14. A hinge mechanism according to claim 12, wherein said first
element of said magnetic circuit comprises a permanent magnet
having a cylindrical shape and a magnetizing direction
perpendicular to an axis of said cylindrical shape, the strength of
said magnetic flux arranged to be changed as a response to a
situation in which said permanent magnet is rotated around said
axis.
15. A hinge mechanism according to claim 14 comprising a coil of
electrical conductor arranged to carry an electrical current for
producing a magnetic field that tends to rotate said permanent
magnet around said axis.
16. A hinge mechanism according to claim 12, wherein said first
element of said magnetic circuit comprises a permanent magnet
having a cylindrical shape and a magnetizing direction parallel
with an axis of said cylindrical shape, the strength of said
magnetic flux being arranged to be changed as a response to a
situation in which said permanent magnet is moved in a direction of
said axis.
17. A hinge mechanism according to claim 16, comprising a coil of
electrical conductor arranged to carry an electrical current for
producing a magnetic field that tends to move said first element in
the direction of said axis.
18. A hinge mechanism according to claim 12, wherein said brake
actuator comprises ferrofluid having viscosity responsive to the
magnetic flux directed to said brake actuator, said viscosity
arranged to produce the braking force on a surface of solid
material in contact with said ferrofluid as a response to a
situation in which said surface moves with respect to said
ferrofluid.
19. A hinge mechanism according to claim 12, wherein said brake
actuator comprises magnetorheological fluid (MRF) having viscosity
responsive to the magnetic flux directed to said brake actuator,
said viscosity arranged to produce the braking force on a surface
of solid material that is in contact with said magnetorheological
fluid as a response to a situation in which said surface moves with
respect to said magnetorheological fluid.
20. A hinge mechanism according to claim 12, wherein said brake
actuator comprises a brake disk and a brake pad arranged to be
pressed against said brake disk as a response to a situation in
which said magnetic flux is conducted into said brake pad.
21. A hinge mechanism according to claim 12, wherein said brake
actuator comprises a brake drum and a brake shoe arranged to be
pressed against said brake drum as a response to a situation in
which said magnetic flux is conducted into said brake shoe.
22. A folding electronic device having a first part and a second
part that are hinged to each other, the folding electronic device
comprising: a brake actuator arranged to generate a braking force
responsive to a magnetic flux directed to said brake actuator, said
braking force being able to damp turning movement of the first part
with respect to the second part, and a magnetic circuit arranged to
generate said magnetic flux and arranged to conduct said magnetic
flux to said brake actuator, wherein a first element of said
magnetic circuit is movable with respect to a second element of
said magnetic circuit and a mutual position of said first element
and said second element is arranged to at least partly determine
strength of said magnetic flux.
23. A folding electronic device according to claim 22, wherein said
magnetic circuit comprises a bypass magnetic path arranged to
conduct another magnetic flux to bypass said brake actuator, a
change in the mutual position of said first element and said second
element arranged to increase strength of the other magnetic flux as
a response to a situation in which said change causes a decrease in
the strength of said magnetic flux directed to said brake
actuator.
24. A folding electronic device according to claim 22, wherein said
folding electronic device is one of the following: a folding mobile
phone, a folding handheld computer, and a folding portable
computer.
25. A folding electronic device according to claim 22, wherein the
second part is a flip cover that is arranged to cover, in a
situation in which the folding electronic device is in a closed
position, at least a part of at least one of the following: a
keyboard and a display screen.
26. A folding electronic device according to claim 22, wherein the
first part comprises a keyboard and the second part comprises a
display screen.
27. A folding electronic device according to claim 22, wherein a
route of an electrical cable between the first part and the second
part is arranged to go through a hollow brake wheel of said brake
actuator.
28. A method for adjusting damping of turning movement of hinged
parts of a folding electronic device, the method comprising:
generating a magnetic flux, generating a braking force responsive
to said magnetic flux, said braking force being able to damp
turning movement of the hinged parts of the folding electronic
device, and adjusting strength of said magnetic flux by adjusting a
mutual position of a first element and a second element of a
magnetic circuit.
29. A method according to claim 28, wherein decreasing of the
strength of said magnetic flux by adjusting the mutual position of
said first element and said second element causes an increase in
strength of another magnetic flux.
30. A method according to claim 28, wherein said magnetic flux is
generated with a permanent magnet having a cylindrical shape and a
magnetizing direction perpendicular to an axis of said cylindrical
shape and the strength of said magnetic flux is changed by rotating
said permanent magnet around said axis.
31. A method according to claim 30, wherein said permanent magnet
is rotated around said axis by using a coil of electrical conductor
carrying an electrical current for producing a magnetic field that
tends to rotate said permanent magnet around said axis.
32. A method according to claim 28, wherein said magnetic flux is
generated with a permanent magnet having a cylindrical shape and a
magnetizing direction parallel with an axis of said cylindrical
shape and the strength of said magnetic flux is changed by moving
said permanent magnet in a direction of said axis.
33. A method according to claim 32, wherein said permanent magnet
is moved in the direction of said axis by using a coil of
electrical conductor carrying an electrical current for producing a
magnetic field that tends to move said first element in the
direction of said axis.
34. A method according to claim 28, wherein the braking force is
generated by using ferrofluid having viscosity responsive to said
magnetic flux, said viscosity producing the braking force on a
surface of solid material in contact with said ferrofluid as a
response to a situation in which said surface moves with respect to
said ferrofluid.
35. A method according to claim 28, wherein the braking force is
generated by using magnetorheological fluid having viscosity
responsive to said magnetic flux, said viscosity producing the
braking force on a surface of solid material in contact with said
magnetorheological fluid as a response to a situation in which said
surface moves with respect to said magnetorheological fluid.
36. A method according to claim 28 wherein the braking force is
generated by using a disk brake that comprises a brake disk and a
brake pad that is pressed against said brake disk as a response to
a situation in which said magnetic flux is conducted into said
brake pad.
37. A method according to claim 28, wherein the braking force is
generated by using a drum brake that comprises a brake drum and a
brake shoe that is pressed against said brake drum as a response to
a situation in which said magnetic flux is conducted into said
brake shoe.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a method for adjusting damping of
movement of hinged parts of a folding electronic device.
Furthermore, the invention relates to an adjustable brake device,
to a hinge mechanism, and to a folding electronic device.
BACKGROUND
[0002] A folding electronic device, e.g. a clamshell mobile phone,
comprises parts that are mechanically connected to each other with
the aid of a hinge mechanism. For example, a folding communication
device can comprise a flip cover that is hinged to a main body of
the folding communication device. Opening of a folding electronic
device having a spring-activated hinge that has no damping
mechanism causes unwanted inertia forces when parts that are
turning with respect to each other reach their open position and an
end stopper of the hinge mechanism abruptly stops the movement.
Furthermore, the opening speed depends on a posture of the folding
electronic device, because in certain postures the gravity force
tends to accelerate the opening whereas in certain other postures
the gravity force tends to inhibit the opening. Therefore, the work
that has to be done by the spring for opening a folding electronic
device depends on the posture in which a user holds the folding
electronic device. Stiffness of the spring should to be selected in
such a way that the spring is able to open the folding electronic
device and, on the other hand, the above-described inertia forces
are within allowed limits in any posture. In order to avoid
disturbing inertia forces when the folding electronic device
reaches its open position, the opening speed should be reduced
smoothly before the end stopper. Arranging satisfactory opening
speed profiles for different postures is an especially challenging
task when a part that has to be moved during opening, e.g. a flip
cover, is heavy. This kind of case is present, for example, when
the part to be moved contains a significant amount of electronics.
Because of different usage situations and customary habits of
users, a hinge mechanism of a folding electronic device should be
provided with an adjustable brake/damping arrangement.
[0003] A solution according to the prior art is to provide a hinge
mechanism with a mechanical friction damper that produces a
friction force that starts to increase when the hinge mechanism
reaches a pre-determined position during opening. In principle, a
friction force generated by a mechanical friction damper could be
adjusted e.g. by adjusting a normal force between surfaces between
which the friction force is present. This kind of solution would,
however, require a mechanical arrangement for adjusting the
above-mentioned normal force. Such mechanical arrangements are
usually expensive and complex. Furthermore, a typical feature of
many adjustable mechanical friction dampers is the fact that a
significant force and/or amount of energy are/is needed for
adjusting an opening speed profile of the hinge mechanism.
[0004] Another solution according to the prior art is to provide a
hinge mechanism with a viscous damper having a substantially
constant damping coefficient. Damping force generated by a viscous
damper having a substantially constant damping coefficient is
proportional to opening speed of the hinge mechanism. In principle,
a damping coefficient of a viscous damper could be adjusted e.g. by
adjusting the amount of damper fluid that is arranged to create the
damping action. This kind of solution would, however, require pump
and valve arrangements for controlling the amount of damper fluid.
Such pump and valve arrangements are usually expensive and
mechanically complex.
SUMMARY
[0005] An objective of the present invention is to provide an
adjustable brake device that can be used for providing an improved
hinge mechanism for a folding electronic device. A further
objective of the present invention is to provide a hinge mechanism
that can be used in conjunction with a folding electronic device. A
further objective of the present invention is to provide a folding
electronic device. A further objective of the present invention is
to provide a method for adjusting damping of turning movement of
hinged parts of a folding electronic device.
[0006] In accordance with a first aspect of the invention an
adjustable brake device is provided. The adjustable brake device
comprises: [0007] a brake actuator arranged to generate a braking
force responsive to a magnetic flux directed to said brake
actuator, and [0008] a magnetic circuit arranged to generate said
magnetic flux and arranged to conduct said magnetic flux to said
brake actuator, wherein a first element of said magnetic circuit is
movable with respect to a second element of said magnetic circuit
and a mutual position of said first element and said second element
is arranged to at least partly determine strength of said magnetic
flux.
[0009] In accordance with a second aspect of the invention a hinge
mechanism is provided. The hinge mechanism comprises: [0010] a
first part and a second part that are able to turn with respect to
each other, [0011] a brake actuator arranged to generate a braking
force responsive to a magnetic flux directed to said brake
actuator, said braking force being able to damp turning movement of
said first part with respect to said second part, and [0012] a
magnetic circuit arranged to generate said magnetic flux and
arranged to conduct said magnetic flux to said brake actuator,
wherein a first element of said magnetic circuit is movable with
respect to a second element of said magnetic circuit and a mutual
position of said first element and said second element is arranged
to at least partly determine strength of said magnetic flux.
[0013] In accordance with a third aspect of the invention a folding
electronic device having a first part and a second part hinged to
each other is provided. The folding electronic device comprises:
[0014] a brake actuator arranged to generate a braking force
responsive to a magnetic flux directed to said brake actuator, said
braking force being able to damp turning movement of the first part
with respect to the second part, and [0015] a magnetic circuit
arranged to generate said magnetic flux and arranged to conduct
said magnetic flux to said brake actuator, wherein a first element
of said magnetic circuit is movable with respect to a second
element of said magnetic circuit and a mutual position of said
first element and said second element is arranged to at least
partly determine strength of said magnetic flux.
[0016] In accordance with a fourth aspect of the invention a method
is provided for adjusting damping of turning movement of hinged
parts of a folding electronic device. The method comprises: [0017]
generating a magnetic flux, [0018] generating a braking force
responsive to said magnetic flux, said braking force being able to
damp turning movement of the hinged parts of the folding electronic
device, and [0019] adjusting strength of said magnetic flux by
adjusting a mutual position of a first element and a second element
of a magnetic circuit.
[0020] A number of embodiments of the invention are described in
accompanied dependent claims.
[0021] The benefit provided by embodiments of the present invention
when compared with prior art solutions of the kind described above
is that braking force generated by a brake device according to an
embodiment of the invention can be adjusted in a relatively simple
way by adjusting a mutual position of movable parts of a magnetic
circuit of the brake device. Furthermore, the magnetic circuit can
be designed in such a way that the total magnetic flux generated in
the magnetic circuit is substantially constant or subject to only
small changes when the mutual position of the movable parts of the
magnetic circuit is varied. In this kind of case, the magnetic
energy stored in the magnetic circuit is substantially constant or
subject to only small changes and, therefore, only a small force
and/or amount of energy are/is needed for adjusting the brake
device.
[0022] Various embodiments of the invention both as to
constructions and to methods of operation, together with additional
objects and advantages thereof, will be best understood from the
following description of specific embodiments when read in
connection with the accompanying drawings.
[0023] The embodiments of the invention presented in this document
are not to be interpreted to pose limitations to the applicability
of the appended claims. The verb "to comprise" is used in this
document as an open limitation that does not exclude the existence
of also unrecited features. The features recited in depending
claims are mutually freely combinable unless otherwise explicitly
stated.
BRIEF DESCRIPTION OF THE FIGURES
[0024] The invention and its advantages are explained in greater
detail below with reference to the embodiments presented in the
sense of examples and with reference to the accompanying drawings,
in which
[0025] FIGS. 1a, 1b, 1c, 1d and 1e show side section views and
cross section views of an adjustable brake device according to an
embodiment of the invention,
[0026] FIGS. 1f and 1g show a side section view and a cross section
view of an adjustable brake device according to an embodiment of
the invention,
[0027] FIGS. 2a, 2b, and 2c show a side section view and cross
section views of an adjustable brake device according to an
embodiment of the invention,
[0028] FIGS. 3a, 3b, 3c, and 3d show side section views and cross
section views of an adjustable brake device according to an
embodiment of the invention,
[0029] FIGS. 4a and 4b show side section views of an adjustable
brake device according to an embodiment of the invention,
[0030] FIGS. 5a, 5b, and 5c show side section views and a cross
section view of an adjustable brake device according to an
embodiment of the invention,
[0031] FIGS. 6a and 6b show a side section view and a cross section
view of an adjustable brake device according to an embodiment of
the invention,
[0032] FIGS. 7a and 7b show a side view and a butt-end view of a
hinge mechanism according to an embodiment of the invention,
[0033] FIG. 8 shows a folding electronic device according to an
embodiment of the invention, and
[0034] FIG. 9 is a flow chart of a method according to an
embodiment of the invention for adjusting damping of turning
movement of hinged elements of a folding electronic device.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0035] FIG. 1a shows a side section view of an adjustable brake
device-according to an embodiment of the invention. FIG. 1b shows a
cross section A-A of the adjustable brake device and FIG. 1c shows
a cross section B-B of the adjustable brake device. Hatched areas
in the figures correspond with cut surfaces. The adjustable brake
device comprises a brake actuator that is arranged to generate a
braking force responsive to a magnetic flux directed to the brake
actuator. In this embodiment of the invention the brake actuator
comprises a brake wheel 101 that is surrounded by fluid 102 that
can be ferrofluid or magnetorheological fluid (MRF). Ferrofluid can
be composed of small polar magnetite Fe.sub.3O.sub.4 particles
surrounded by a surfactant and suspended in a nonpolar liquid
medium. Tiny particles of magnetite are suspended throughout liquid
medium. In order to prevent the particles from aggregating, they
can be surrounded by a polar end of long chain fatty acid
molecules, to which the particles are attracted by ion-dipole
forces. The long, nonpolar tails of the molecules are attracted by
London forces to the molecules of the oil that serves as the liquid
medium, but cannot compete with the polar ends in their attraction
for the particles. Magnetorheological fluid can be composed of
carbonyl iron powder in a carrier liquid like conventional mineral
oil.
[0036] The viscosity/stiffness of the ferrofluid or the
magnetorheological fluid is responsive to a magnetic flux 103. The
stiffness/viscosity of the ferrofluid or the magnetorheological
fluid can be adjusted by adjusting strength of the magnetic flux
103. The stiffness/viscosity of the ferrofluid or the
magnetorheological fluid causes a braking force on a surface of the
brake wheel 101 as a response to a situation in which the surface
moves with respect to the ferrofluid or the magnetorheological
fluid, i.e. the brake wheel rotates around an axis 104.
[0037] The adjustable brake device comprises a magnetic circuit
arranged to generate the magnetic flux 103 and to conduct the
magnetic flux 103 to the brake actuator. The magnetic circuit
comprises a magnetizing device 105 that is arranged to generate the
magnetic flux 103 and a magnetic path that is arranged to conduct
the magnetic flux 103 from the magnetizing device 105 to the brake
actuator. Parts 106 and 107 of the brake device act as portions of
the magnetic path via which the magnetic flux 103 flows between the
magnetizing device 105 and the brake actuator. The parts 106 and
107 and the brake wheel 101 can be made of ferromagnetic material
like iron. The parts 106 and 107 are separated from each other with
parts 108 and 109 that are made of material having a smaller
relative permeability .mu..sub.r than that of the parts 106 and
107. The parts 108 and 109 can be made of e.g. plastic.
[0038] The axis 104 is supported with the aid of an axis supporting
part 112 that is made of material having a smaller relative
permeability .mu..sub.r than that of the parts 106 and 107. The
axis supporting part 112 can be made of e.g. plastic.
[0039] In this embodiment of the invention the magnetizing device
105 is a permanent magnet that has a cylindrical shape. A
magnetizing direction 110 of the permanent magnet is perpendicular
to the axis 104. In an alternative embodiment of the invention the
magnetizing device 105 can be an electrical magnet that comprises a
coil of electrical conductor for carrying magnetizing electrical
current and a current source for generating the magnetizing
electrical current.
[0040] A first element of the magnetic circuit and a second element
of the magnetic circuit are movable with respect to each other and
a mutual position of the first and second elements is arranged to
at least partly determine strength of the magnetic flux 103. In
this embodiment of the invention the permanent magnet 105
represents the first element that is movable with respect to the
second element that consists of parts 106,107,108, and 109.
[0041] The strength of said magnetic flux 103 can be adjusted by
rotating the permanent magnet 105 around the axis 104. FIGS. 1a,
1b, and 1c illustrate a situation in which the magnetic flux 103
directed to the brake actuator has its maximum strength. FIGS. 1d
and 1e illustrate a situation in which the magnetic flux directed
to the brake actuator has its minimum strength. The reference
numbers in FIGS. 1d and 1e corresponds with those in FIGS. 1a, 1b,
and 1c. In the situation illustrated in FIGS. 1d and 1e, the
permanent magnet 105 has been rotated by ninety degrees
(90.degree.) with respect to the situation illustrated in FIGS. 1a,
1b, and 1c. In FIGS. 1d and 1e, a main portion of the total
magnetic flux generated by the permanent magnet 105 bypasses the
brake actuator. The parts 106 and 107 form a bypass path for a
magnetic flux 111 that bypasses the brake actuator as illustrated
in FIGS. 1d and 1e. The strength of the magnetic flux 103 can be
adjusted in a stepless way by adjusting a rotation angle of the
permanent magnet 105 between the two extremes shown in FIGS.
1a-1e.
[0042] FIG. 1f shows a side section view of an adjustable brake
device according to an embodiment of the invention. FIG. 1g shows a
cross section C-C of the adjustable brake device. Hatched areas in
the figures correspond with cut surfaces. The adjustable brake
device comprises a brake actuator that is arranged to generate a
braking force responsive to a magnetic flux directed to the brake
actuator. In this embodiment of the invention the brake actuator
comprises a brake wheel 101 that is surrounded by fluid 102 that
can be ferrofluid or magnetorheological fluid (MRF).
[0043] The adjustable brake device comprises a magnetic circuit
arranged to generate a magnetic flux 103 and to conduct the
magnetic flux 103 to the brake actuator. The magnetic circuit
comprises a permanent magnet 105 that is arranged to generate the
magnetic flux 103 and a magnetic path that is arranged to conduct
the magnetic flux 103 from the permanent magnet 105 to the brake
actuator. Parts 106 and 107 of the brake device act as portions of
the magnetic path via which the magnetic flux 103 flows between the
permanent magnet 105 and the brake actuator. The parts 106 and 107
and the brake wheel 101 can be made of ferromagnetic material like
iron. The parts 106 and 107 are separated from each other with
parts 108 and 109 that are made of material having a smaller
relative permeability .mu..sub.r than that of the parts 106 and
107. The parts 108 and 109 can be made of e.g. plastic. The
strength of said magnetic flux 103 can be adjusted by rotating the
permanent magnet 105 around an axis 104. The axis 104 is supported
with the aid of an axis supporting part 112 that is made of
material having a smaller relative permeability P than that of the
parts 106 and 107. The axis supporting part 112 can be made of e.g.
plastic. Seal elements 122 prevent the ferrofluid or the
magnetorheological fluid from leaking out from gaps between the
brake wheel 101 and the parts 106, 107, 108, and 109. The brake
wheel 101 is able to rotate in an aperture of an end plate 123. The
brake wheel is hollow in such a way that a cable 120 can go through
the adjustable brake device. A route of the cable 120 is arranged
to go through the hollow brake wheel and an aperture in the part
109 as shown in FIGS. 1f and 1g.
[0044] The adjustable brake device shown in FIGS. 1f and 1g can be
used, for example, in a folding electronic device. A route of an
electrical cable between hinged parts of the folding electronic
device can be arranged to go through a hollow brake wheel in a
similar manner as the route of the cable 120 in the adjustable
brake device shown in FIGS. 1f and 1g.
[0045] FIG. 2a shows a side section view of an adjustable brake
device according to an embodiment of the invention. The brake
device comprises an X-coil 201 and an Y-coil 202 that are arranged
to carry electrical currents Ix and Iy for producing a magnetic
flux that tends to rotate a permanent magnet 205 around an axis
204. FIGS. 2b and 2c show a cross section A-A of the brake device.
Hatched areas in the figures correspond with cut surfaces. FIG. 2b
illustrates a situation in which the electrical current Ix is
flowing and the electrical current Iy is zero. The electrical
current Ix generates a magnetic flux 206 that tends to rotate the
permanent magnet to the position shown in FIG. 2b. FIG. 2c
illustrates a situation in which the electrical current Iy is
flowing and the electrical current Ix is zero. The electrical
current Iy generates a magnetic flux 207 that tends to rotate the
permanent magnet to the position shown in FIG. 2c. Arrow 208
illustrates the magnetizing direction of the permanent magnet 205.
The permanent magnet 205 can be set into different rotation angles
by selecting suitable values for Ix and Iy. For example, if Ix and
Iy have such values that the magnetic fluxes 206 and 207 have equal
strengths the combined effect of the magnetic fluxes 206 and 207
tends to set the permanent magnet into a rotation angle that is 45
degrees counter-clockwise from the rotation angle shown in FIG.
2b.
[0046] FIG. 3a shows a side section view of an adjustable brake
device according to an embodiment of the invention. FIG. 3b shows a
cross section A-A of the adjustable brake device and FIG. 3c shows
a cross section B-B of the adjustable brake device. Hatched areas
in the figures correspond with cut surfaces. The adjustable brake
device comprises a brake actuator that is arranged to generate a
braking force responsive to a magnetic flux directed to the brake
actuator. In this embodiment of the invention the brake actuator
comprises a brake wheel 301 that is surrounded by fluid 302 that
can be ferrofluid or magnetorheological fluid (MRF). A seal element
313 prevents the ferrofluid or the magnetorheological fluid from
leaking out from a gap between the brake wheel 301 and a part 304.
The brake wheel 301 is able to rotate around an axis 309 that is
supported with the aid of an axis supporting part 310.
[0047] The adjustable brake device comprises a magnetic circuit
having a magnetizing device 305 that is arranged to generate a
magnetic flux 303 and a magnetic path that is arranged to conduct
the magnetic flux 303 from the magnetizing device 305 to the brake
actuator. In this embodiment of the invention the magnetizing
device 305 is a permanent magnet that has a cylindrical shape. A
magnetizing direction 306 of the permanent magnet is parallel with
the axis 309.
[0048] The permanent magnet 305 and parts 307 and 308 form a
movable element that can be moved along the axis 309. The parts
307, 308, and 304 act as portions of the magnetic path via which
the magnetic flux 303 flows between the permanent magnet 305 and
the brake actuator. The parts 307, 308, and 304 and the brake wheel
301 can be made of ferromagnetic material like iron.
[0049] A first element of the magnetic circuit and a second element
of the magnetic circuit are movable with respect to each other and
a mutual position of the first and second elements is arranged to
at least partly determine strength of the magnetic flux 303. In
this embodiment of the invention the movable element consisting of
the permanent magnet 305 and of the parts 307 and 308 represents
the first element that is movable with respect to the part 304 that
represents the second element. The strength of the magnetic flux
303 is adjusted by adjusting the position of the movable element
305, 307, 308 on the axis 309.
[0050] The magnetic circuit comprises a bypass magnetic path that
conducts another magnetic flux 315 that is generated by the
permanent magnet 305 to bypass the brake actuator. A change in the
mutual position between the movable element 305, 307, 308 and the
part 304 is arranged to increase the magnetic flux 315 as a
response to a situation in which the named change causes a decrease
in the magnetic flux 303. The above-mentioned effect is achieved
with an overhang 316. When the movable element 305, 307, 308 is
moved towards the axis supporting part 310, the part 308 gets
closer to the overhang and, therefore, the reluctance of the bypass
magnetic path carrying the magnetic flux 315 decreases and the
magnetic flux 315 increases. On the other hand, the part 308 gets
farther from the brake wheel 301 and, therefore, the reluctance of
the magnetic path carrying the magnetic flux 303 increases and the
magnetic flux 303 decreases.
[0051] FIG. 3a illustrates a situation in which the magnetic flux
303 has its maximum strength. FIG. 3d illustrates a situation in
which the magnetic flux 303 has its minimum strength and the
magnetic flux 315 has its maximum strength.
[0052] A shape of the part 308 and a shape of the overhang 316 can
be designed in such a way that the total magnetic flux generated by
the permanent magnet 305 is substantially constant or subject to
only small changes when the position of the movable element 305,
307, 308 is varied. In this kind of case, the magnetic energy
stored in the magnetic circuit is substantially constant or subject
to only small changes and, therefore, only a small force and/or
amount of energy are/is needed for changing the position of the
movable element 305, 307, 308. I.e. only a small force and/or
amount of energy are/is needed for adjusting the brake device.
Suitable shapes for the part 308 and for the overhang 316 can be
found with prototype testing and/or with simulations. For example,
numerical field calculation based on a finite element method (FEM)
can be used in simulations.
[0053] FIGS. 4a and 4b show side section views of an adjustable
brake device according to an embodiment of the invention. The brake
device comprises coils 401 and 402 that are arranged to carry
electrical currents I1 and I2 for producing magnetic fluxes that
tend to move a movable element 405, 407, 408 along an axis 404.
FIG. 4a illustrates a situation in which the electrical currents I1
and I2 magnetize in a same direction when there is an attractive
force between the coils 401 and 402. FIG. 4b illustrates a
situation in which the electrical currents I1 and I2 magnetize in
opposite directions when there is a repulsive force between the
coils 401 and 402. Closed curves 406 represent magnetic fluxes
produced by the electrical currents I1 and I2.
[0054] FIG. 5a shows a side section view of an adjustable brake
device according to an embodiment of the invention. FIG. 5b shows a
cross section A-A of the brake device. Hatched areas in the figures
correspond with cut surfaces. The adjustable brake device comprises
a brake actuator that is arranged to generate a braking force
responsive to a magnetic flux directed to the brake actuator. In
this embodiment of the invention the brake actuator is a disk brake
comprising a brake disk 501 and brake pads 502. The brake disk 501
is able to rotate around an axis 509 that is supported with the aid
of an axis supporting part 510. The brake pads 502 are made of
material having a greater relative permeability .mu..sub.r than
that of air. The brake pads 502 can be made of e.g. iron. The brake
pads are moveably pivoted to a part 504 with the aid of pins 511.
Therefore, the brake pads are pressed against the brake disk when a
magnetic flux 503 flows via the brake pads.
[0055] A permanent magnet 505 and parts 506 and 507 form a movable
element that can be moved along the axis 509. Strength of the
magnetic flux 503 can be adjusted by adjusting a position of the
movable element on the axis 509. The parts 504, 506, and 507 can be
made of e.g. iron. FIG. 5a illustrates a situation in which the
magnetic flux 503 directed to the brake actuator has its maximum
strength. FIG. 5c illustrates a situation in which the magnetic
flux directed to the brake actuator has its minimum strength.
Closed curves 512 in FIG. 5b represent a magnetic flux that
bypasses the brake actuator.
[0056] FIG. 6a shows a side section view of an adjustable brake
device according to an embodiment of the invention. FIG. 6b shows a
cross section A-A of the brake device. Hatched areas in the figures
correspond with cut surfaces. The adjustable brake device comprises
a brake actuator that is arranged to generate a braking force
responsive to a magnetic flux directed to the brake actuator. In
this embodiment of the invention the brake actuator is a drum brake
having external brake shoes. The brake actuator comprises a brake
drum 601 and brake shoes 602. The brake drum 601 is able to rotate
around an axis 609 that is supported with the aid of an axis
supporting part 610. The brake shoes 602 are made of material
having a greater relative permeability .mu..sub.r than that of air.
The brake drum 601 and the brake shoes 602 can be made of e.g.
iron. The brake shoes are moveably pivoted to a part 604 with the
aid of pins 611. Therefore, the brake shoes are pressed against the
brake drum when a magnetic flux 603 flows via the brake shoes.
FIGS. 7a shows a side view of a hinge mechanism according to an
embodiment of the invention. FIG. 7b shows a butt-end view A of the
hinge mechanism. The hinge mechanism comprises a first part 701 and
a second part 702 that are able to turn with respect to each other.
The first part 701 comprises a brake actuator arranged to generate
a braking force responsive to a magnetic flux directed to the brake
actuator. The braking force is able to damp turning movement of
said first part with respect to said second part. The turning
movement represents variation of angle .alpha. shown in FIG. 7b.
The first part 701 comprises a magnetic circuit arranged to
generate the magnetic flux and to conduct the magnetic flux to the
brake actuator. A first element and a second element of the
magnetic circuit are movable with respect to each other and a
mutual position of the first element and the second element is
arranged to at least partly determine strength of the magnetic flux
that is directed to the brake actuator. Therefore, the braking
effect generated by the brake actuator can be adjusted by adjusting
the mutual position of the first element and the second
element.
[0057] In FIG. 7a, the brake actuator and the magnetic circuit are
shown as dashed lines in the first part 701. The first part 701
comprises a control arm 703 with the aid of which the mutual
position of the first element and the second of the magnetic
circuit can be adjusted.
[0058] In a hinge mechanism according to an embodiment of the
invention the magnetic circuit comprises a bypass magnetic path for
a magnetic flux that bypasses the brake actuator. A change in the
mutual position of the first element and the second element of the
magnetic circuit is arranged to increase strength of the bypassing
magnetic flux as a response to a situation in which the
above-mentioned change causes a decrease in the strength of the
magnetic flux that is directed to the brake actuator.
[0059] In a hinge mechanism according to an embodiment of the
invention the first element of the magnetic circuit comprises a
permanent magnet having a cylindrical shape and a magnetizing
direction that is perpendicular to an axis of the cylindrical
shape. The strength of the magnetic flux directed to the brake
actuator is changed as a response to a situation in which the
permanent magnet is rotated around the above-mentioned axis. The
permanent magnet can be rotated, for example, with the aid of a
coil of electrical conductor arranged to carry an electrical
current for producing a magnetic field that tends to rotate the
permanent magnet around the axis.
[0060] In a hinge mechanism according to an embodiment of the
invention the first element of the magnetic circuit comprises a
permanent magnet having a cylindrical shape and a magnetizing
direction that is parallel with an axis of the cylindrical shape.
The strength of the magnetic flux directed to the brake actuator is
changed as a response to a situation in which the permanent magnet
is moved in a direction of the above-mentioned axis. The permanent
magnet can be moved, for example, with the aid of a coil of
electrical conductor arranged to carry an electrical current for
producing a magnetic field that tends to move the permanent magnet
in the direction of the axis.
[0061] In a hinge mechanism according to an embodiment of the
invention the brake actuator comprises ferrofluid or
magnetorheological fluid the viscosity/stiffness of which is
responsive to the magnetic flux directed to the brake actuator. The
viscosity produces a braking force on a surface of solid material
that is in contact with the ferrofluid or the magnetorheological
fluid as a response to a situation in which the surface moves with
respect to the ferrofluid or the magnetorheological fluid.
[0062] In a hinge mechanism according to an embodiment of the
invention the brake actuator is a disk brake that comprises a brake
disk and a brake pad. The brake pad is pressed against the brake
disk as a response to a situation in which a magnetic flux is
conducted into the brake actuator.
[0063] In a hinge mechanism according to an embodiment of the
invention the brake actuator is a drum brake that comprises a brake
drum and a brake shoe. The brake shoe is pressed against the brake
drum as a response to a situation in which a magnetic flux is
conducted into the brake actuator.
[0064] FIG. 8 shows a folding electronic device according to an
embodiment of the invention. The folding electronic device has a
first part 801 and a second part 802 that are hinged to each other.
The folding electronic device comprises a brake actuator arranged
to generate a braking force responsive to a magnetic flux directed
to the brake actuator. The braking force is able to damp turning
movement of the first part with respect to the second part. The
folding electronic device comprises a magnetic circuit arranged to
generate the magnetic flux and to conduct the magnetic flux to the
brake actuator. A first element of the magnetic circuit is movable
with respect to a second element of the magnetic circuit and a
mutual position of the first element and the second element is
arranged to at least partly determine strength of the magnetic flux
directed to the brake actuator. Therefore, the braking effect
generated by the brake actuator can be adjusted by adjusting the
mutual position of the first element and the second element. In the
folding electronic device shown in FIG. 8, the brake actuator and
the magnetic circuit can be located in the part pointed out with a
dashed line circle 803.
[0065] In a folding electronic device according to an embodiment of
the invention the magnetic circuit comprises a bypass magnetic path
for a magnetic flux that bypasses the brake actuator. A change in
the mutual position of the first element and the second element of
the magnetic circuit is arranged to increase strength of the
bypassing magnetic flux as a response to a situation in which the
above-mentioned change causes a decrease in the strength of the
magnetic flux that is directed to the brake actuator.
[0066] A folding electronic device according to an embodiment of
the invention is a folding mobile phone.
[0067] A folding electronic device according to an embodiment of
the invention is a folding handheld computer, i.e. a folding
palmtop computer.
[0068] A folding electronic device according to an embodiment of
the invention is a folding portable computer, i.e. a folding laptop
computer.
[0069] In a folding electronic device according to an embodiment of
the invention the second part 802 is a flip cover that is arranged
to cover, in a situation in which the folding electronic device is
in a closed position, at least a part of at least one of the
following: a keyboard 804 and a display screen 805.
[0070] In a folding electronic device according to an embodiment of
the invention the first part 801 comprises a keyboard 804 and the
second part 802 comprises a display screen 806.
[0071] In a folding electronic device according to an embodiment of
the invention a route of an electrical cable between the first part
801 and the second part 802 is arranged to go through a hollow
brake wheel of the brake actuator in a similar manner as the route
of the cable in the adjustable brake device shown in FIGS. 1f and
1g.
[0072] FIG. 9 is a flow chart of a method according to an
embodiment of the invention for adjusting damping of turning
movement of hinged parts of a folding electronic device. In the
method: a magnetic flux is generated 901, a braking force able to
damp the turning movement and responsive to the magnetic flux is
generated 902, and strength of the magnetic flux is adjusted 903 by
adjusting a mutual position of a first element and a second element
of a magnetic circuit.
[0073] In a method according to an embodiment of the invention
decreasing of the strength of the above-mentioned magnetic flux by
adjusting the mutual position of said first element and said second
element causes an increase in strength of another magnetic
flux.
[0074] In a method according to an embodiment of the invention the
magnetic flux is generated with a permanent magnet having a
cylindrical shape and a magnetizing direction perpendicular to an
axis of the cylindrical shape. Rotating the permanent magnet around
the above-mentioned axis changes the strength of the magnetic flux.
The permanent magnet can be rotated, for example, with the aid of a
coil of electrical conductor arranged to carry an electrical
current for producing a magnetic field that tends to rotate the
permanent magnet around the axis.
[0075] In a method according to an embodiment of the invention the
magnetic flux is generated with a permanent magnet having a
cylindrical shape and a magnetizing direction parallel with an axis
of the cylindrical shape. Moving the permanent magnet in the
direction of the above-mentioned axis changes the strength of the
magnetic flux. The permanent magnet can be moved, for example, with
the aid of a coil of electrical conductor arranged to carry an
electrical current for producing a magnetic field that tends to
move the first element in the direction of the axis.
[0076] In a method according to an embodiment of the invention
ferrofluid or magnetorheological fluid is used for generating the
braking force that is able to damp turning movement of the hinged
parts of the folding electronic device. The viscosity/stiffness of
the ferrofluid or the magnetorheological fluid is responsive to the
magnetic flux. The viscosity produces the braking force on a
surface of solid material that is in contact with the ferrofluid or
the magnetorheological fluid as a response to a situation in which
the surface moves with respect to the ferrofluid or the
magnetorheological fluid.
[0077] In a method according to an embodiment of the invention a
disk brake is used for generating the braking force that is able to
damp turning movement of the hinged parts of the folding electronic
device. The disk brake comprises a brake disk and a brake pad. The
brake pad is pressed against the brake disk as a response to a
situation in which a magnetic flux is conducted into the brake
pad.
[0078] In a method according to an embodiment of the invention a
drum brake is used for generating the braking force that is able to
damp turning movement of the hinged parts of the folding electronic
device. The drum brake comprises a brake drum and a brake shoe. The
brake shoe is pressed against the brake drum as a response to a
situation in which a magnetic flux is conducted into the brake
shoe.
[0079] While there have been shown and described and pointed out
fundamental novel features of the invention as applied to
embodiments thereof, it will be understood that various omissions
and substitutions and changes in the form and details of the
devices and methods described may be made by those skilled in the
art without departing from the spirit of the invention. For
example, it is expressly intended that all combinations of those
elements and/or method steps which perform substantially the same
function in substantially the same way to achieve the same results
are within the scope of the invention. Moreover, it should be
recognized that structures and/or elements and/or method steps
shown and/or described in connection with any disclosed form or
embodiment of the invention may be incorporated in any other
disclosed or described or suggested form or embodiment as a general
matter of design choice. It is the intention, therefore, to be
limited only as indicated by the scope of the independent claims
appended hereto. The specific examples provided in the description
given above should not be construed as limiting. Therefore, the
invention is not limited merely to the embodiments described above,
many variants being possible without departing from the scope of
the inventive idea defined in the independent claims.
* * * * *